In injection molding and in particular hot runner molds for injection molding managing the thermal transition at the mold gate between the hot runner side and the cold cavity side of the mold is a challenge.
In valve gated hot runner nozzles when the valve pin is seated in the mold gate in a closed position, the valve pin conducts heat from the molten material in the nozzle melt channel to the area of the mold gate. Such heat transfer makes it difficult to cool the mold gate area. Further, if the molded part is ejected before adequate cooling is achieved, the mold gate vestige on the molded part may be damaged and considered cosmetically undesirable.